Diesel fuel composition

ABSTRACT

A diesel fuel containing a carbonated, basic barium salt to reduce smoke.

United States Patent Vanderlinden et al.

[451 Jan. 25, 1972 DIESEL FUEL COMPOSITION Andre Jacques Emile Vanderlinden, Watermael-Boitsford; Gilbert Jules Ghislain Stubbe, Liege, both of Belgium lnventors:

Assignee: Cosden Oil & Chemical Company, Big

Springs, Tex.

Filed: July 15, 1965 Appl. No.: 472,365

Foreign Application Priority Data Mar. 31, 1965 Italy ..28472 US. Cl ..44/5l, 44/66, 44/70,

44/76 Int. Cl .Cl0l l/l8,ClOl l/24, C10] 1/32 Field of Search ..44/57, 66, 4, 5 l 70, 76;

Primary ExaminerDaniel E. Wyman Assistant Examiner-W. J. Shine Aztorney-Sol B. Wiczer ABSTRACT A diesel fuel containing a carbonated, basic barium salt to reduce smoke.

14 Claims, 3 Drawing Figures DIESEL FUEL COMPOSITION This invention relates to liquid fuels containing a smokereducing additive and particularly liquid fuels containing compounds of barium with mixed anions including both carbonate and either or both of sulfonic and carboxylic acid anions.

The additive compounds of this invention are particularly useful in diesel fuel oils which commonly evolve a smoky and often noxious exhaust and comprise gasoils which may have a substantial sulfur content. Moreover, the additive compounds improve the power output while reducing carbon deposits and other common effects associated with smoky exhaust.

The primary object of this invention is to reduce the smoke present in combustion gases produced by combustion of liquid fuels by adding to the fuel a compound having the formula RY-Ba-CO (Ba-CO )x-BaY'R wherein R is an organic radical imparting oil solubility to the compound, usually high molecular weight aliphatic, alicyclic, aromatic or mixed-type hydrocarbon usually having at least l carbon atoms, Y is CO;, or SO radicals, Y is CO and x is an integer having a value in the range of 0 through 8, preferably 0 to 6.

In the combustion of liquid fuels, particularly under variable conditions of accelerated combustion, a smoky exhaust is usual, especially in diesel and similar devices often burning unrefined or only moderately refined burning oils such as fuel oils or pot oils. Even under careful adjustment of the hydrocarbon-air feed ratio to the engine or burners, smoky combustion often occurs. Particularly in the case of diesel fuels with variable conditions of acceleration with large fuel feed during rapid acceleration for increased power, the fuel being then injected in greater than a critical quantity, combustion normally occurs with large discharge of black smoke. Such increase in power of a diesel engine is not proportional to the increase in fuel consumption. Such emission of smoke is troublesome under any conditions, and particularly so in confined spaces. The smoky combustion indicates increased and wasted fuel consumption due to the incomplete combustion, and, besides the noxious fouling of the air, fouling of engine parts is also a common and undesirable result.

It is found by use of the additive of the present invention in small quantity to the liquid fuel that the quantity of smoke is markedly reduced. The combustion is more efficient in a diesel engine, power output is increased, and the fouling of the engine is also reduced.

Our preferred additives are the mixed barium carbonate salts of an organic sulfonic acid or an organic carboxylic acid such as barium sulfonatocarbonate or barium naphthenatocarbonate and mixtures of these barium salts in which the organic sulfonato radical is preferably a higher alkyl such as keryl benzene sulfonate or a petroleum sulfonate, and the naphthenato radical is derived from a petroleum naphthenic acid, usually mixed petroleum naphthenic acids.

The compounds are known types but are preferably formed, according to the present invention, by dissolving the organic acid in a carrier oil such as gasoil or an oil of the same character as the fuel with which the additive is to be treated, or an oil carrier readily miscible with the combustible oil to be treated. The organic acid solution in said oil carrier is then reacted with a barium oxide solution in anhydrous methanol. Finally, the product is converted to the carbonate by bubbling CO into the solution to substantial neutrality. Ultimately the methanol may be evaporated and the liquid product solution of the barium salt in the carrier oil may be filtered. A slight quantity of water sometimes improves the fluidity of the product. The preferred naphthenic and sulfonic acids give an improved fluidity to the final product. While other carboxylic and sulfonic acids are useful and react with the barium oxide in the same way, these often produce an undesirably thick product, which would require expensive blending equipment for dissolving in the fuel. While the product may be formed in situ in the fuel to be treated up to the useful quantity stated, it is preferred first to form a concentrate of 30 to 60 percent of barium compound in the liquid fuel carrier as described, and use such concentrated solution in a suitably small quantity as an additive base supplied to the fuel being treated, so that the concentrate is diluted to the requisite concentration of barium compound in the fuel.

For example, additive is formed as a concentrate in a gasoil, diesel oil or kerosene of somewhat lower viscosity as the carrier oil, 30 to 50 percent of barium sulfonatocarbonate or barium naphthenatocarbonate formed as described being dissolved in the oil, the balance of 50 to 70 percent of the composition being the carrier gasoilor the like. The composition of such additive would comprise 10 to 25 weight-percent of barium ion, 2 to 9 weight-percent of CO ion and l0 to 30 weight-percent of RY ion. Such mixture is then used by supplying and dissolving a portion of the solution as additive in the liquid fuel to be treated such as the diesel fuel, typically gasoil, in quantity to impart a 0.0] to 1 percent by weight based on the quantity of dissolved barium in the liquid fuel, preferably for diesel oil a concentration of 0.02 to 0.25 percent by weight of barium therein.

In the same manner, a liquid concentrate of barium naphthenatocarbonate and barium sulfonatocarbonate may be formed or by dissolving mixed organic acids, naphthenic and alkyl benzene sulfonic, in the carrier oil whereby a mixed salt comprising barium naphthenatocarbonate and barium sulfonatocarbonate is formed in solution therein. Alternately, the separately formed solutions as first described can be mixed to form a composite blend of both types of mixed barium salt.

Gasoils, typically used for diesel fuel, often contain substantial quantities of sulfur. Because of this sulfur content, the barium is converted into barium sulfate. Even when the barium compound is used at a concentration of 0.25 percent in the diesel fuel, all of the barium would be discharged as barium sulfate if the fuel only contain 0.057 percent of sulfur. Commercial diesel fuels usually contain much more sulfur.

Compared to the combustion products of other additives that have been proposed in the art for smoke reduction, barium sulfate is substantially inert, noncorrosive, nontoxic and, being quite heavy, it settles very rapidly rather than remain as a suspended dust to pollute the atmosphere.

Moreover, in this type of compound, according to the invention, the barium appears to be present in quite high concentration with respect to the rest of the organic molecule and perhaps for this reason exhibits such high smoke-inhibiting effect, quite superior in the same concentration to other proposed smoke-inhibiting compounds used at much higher concentrations.

The barium sulfonatocarbonate may be produced in powder form and shows no sign of crystallinity upon analysis by X-ray diffraction, thereby proving that the product is not a dispersion of barium carbonate particles nor a simple suspension thereof in the oil. Without intending to be limited to any theory, the substance comprising the additive of this invention appears to have an amorphous polymeric structure, which may explain the ease with which it dissolves in the carrier oil even when applied thereto for dissolution from a preformed powder form. Upon heating, this additive product decomposes with large CO release which may possibly result in better atomization of the gasoil droplets with which it is associated during combustion whereby the catalytic smoke-reducing action of the dispersed barium is so fully achieved.

Moreover, the additive hereof does not unduly increase the viscosity of the liquid fuel with which it is blended. For instance, a diesel gasoil with a barium content of 20 percent resulting from dissolving a substantial concentration of the additive herein still remains within 10 and 20 centistokes at l00 F., a solution substantially as fluid as the untreated diesel fuel. In contrast, a 17 percent solution of neutral barium sulfonate in the same diesel fuel would have a viscosity of about 112 centistokes at 210 F., a quite viscous liquid. The additive compound hereof in this quantity would contain nine times as much barium as the 17 percent neutral barium sulfonate solution. The latter would contain only 2.2 percent barium. Thus the mixed sulfo-carbonated compound of barium, according to the present invention, comprises an additive which may be EXAMPLE 1 Four additives were prepared from the same petroleum (keryl) benzene sulfonic acid with a mean molecular weight of 452. The final additives had the following characteristics:

Mean mole- Alkalinity cular 36 weight mg. KOH/g. Additive weight additive Neutral Ca sulfonate 944 4.23 Ca sulfonatocarbonate L674 19.8l 488.8 neutral Ba sulfonatc 1,04l 13.19 Ba sulfonatocarbonate 2,482 45.90 329.6

The additives were incorporated separately in a commercial Diesel fuel at various concentrations expressed as weight-percentage of metal in the gasoil, the Ca concentrations being 3.4 times less than those of Ba.

The characteristics of the gasoil were as follows:

Cctane number 50 Density at [5 C. 0.8296 ASTM Distillation initial point. C. l6l 50% point, C. 260.5 90% point, C. 327.5 final point,C. 368 Sulfur content, weight 0.54 Kinematic viscosity at 37.8" C. Redwood sec. 32

The tests were carried out with a Petter AVl Diesel engine following the oil test procedure CEC/AT4 slightly modified to rapidly determine the activity of the additives, at high full consumption, the gasoil consumption being increased from 1,088 gjhour to l,l48 gJhour. Measurement of the exhaust smoke was carried out with the Hartridge smokemeter which measures the decrease of intensity of a light beam passing through the smoke moving in a conduit. The Hartridge smokemeter is calibrated from to 100, the lower values corresponding to the least opaque exhaust.

The test results are given in the following table:

TABLE I Hartridge index Hartridge index Qoncentra- Ca sultration Ba sultton weight Neutral fonatoweight; Neutral ionatopereent of Ca sulearbonpercent of Ba sulcarbo- Ca in Innate ate Ba in tonate hate gasoil A B gasoil C D The results show the marked superiority of combining in the same additive the Ba metal and the CO anion. lndeed, comparing the results of columns A and C, there is an evident reduction of the smoke. apparently due to the catalytic effect of the Ba since both sulfonates differ only by the nature'of the metal. Comparison of columns A and B on one side and C and D on the other side clearly demonstrates the favorable effect of the CO anion present in the additives. Lastly, the results of column D emphasize the outstanding activity of the additive to reduce the amount of smoke by more than 50 percent at a concentration as low as 0.02 percent by weight of Ba in the gasoil.

EXAMPLE 2 After the test perfonned on the Ba sulfonatocarbonate used at a concentration of 0.05 percent by weight of Ba in the gasoil, the Petter Diesel engine was dismantled and inspected. The inspection of different parts of the engine showed that the additive had no detrimental effect on the performance of the lubricating oil, that it improves the combustion and keeps the engine in perfect condition.

The various measurements made according to the standard rating CEC/AT4 are set forth in tabular form below:

TABLE ll Gasoil & Test Gasoil Additive Piston ring sticking on l0 l0 l0 Scraper ring sludge on 10 10 t0 Piston skirt after washing on 10 9.9 9.9 Piston lands (average of three) on It] 8.8 8.5 Piston grooves (average of three) on 10 8.7 9 Piston crown cutting on ID 9.5 9.5 inside of piston on 10 8 7.5 Weight loss (in mg.) of 15! ring 8 l .2 50.8

2nd ring 29.2 12.5

3rd ring 26.5 ".7

4th ring 25.4 7.8

(scraper) TABLE II] Test without Test with Used Oil Analysis additive additive Specific gravity at lS.4 C. 0.892 0.898 Viscosity (ASTM.D.445) Englcr at 50 C. 9.83 9.25 Neutralization number (ASTM.D.664) mg. KOHIg. 1.38 1.10 Strong acid number. mg. KOH/g. nil nil Total acid number, mg. KOHIg. L38 l.l0 Ash, weight (ASTM.D.810) weight 0.97 [.10 Dilution (ASTMDJZZ) vol. 0.8 0.8 Water content (ASTM.D.95) vol. traces nil lnsolublcs and solubles (ASTMJLEQB-SZT) weight L58 L67 lnsolubles in benzene (ASTM.D.89352T) weight [.42 1.51

Metallic parts nil nil Those results in table "I show a slight increase in the ash, insolubles and solubles content of the used oil. This has no detrimental effect on the condition of the engine as shown by the resuits given in table Ii.

EXAMPLE 3 A Ba naphthenatocarbonate salt was prepared from a naphthenic acid mixture having a mean molecular weight of 283, the salt having the following characteristics:

Mean molecular weight weight percent of metal alkalinity. mg. KOH/g. additive of Ba naphthenatocarbonate of this example was also prepared and tested at various concentrations in the gasoil.

Table IV summarizes the test results and shows that the activity of the Ba naphthenatocarbonate used alone or in mixture with Ba sulfonatocarbonate is very close to that of the Ba sulfonatocarbonate and that the Ba naphthenatocarbonate similarly improves the Diesel gasoil combustion.

. 1 Weight Ba sull'onatocarbonate and 48",, weight Ila |iaphthcnatocarbonate.

EXAMPLE 4 A good additive should maintain its activity during long periods of time. The tests carried out in examples I and 3 may be modified to show the duration of the activity of the different additives, and the results are summarized in the followmg:

Curve No. 7 illustrates the H. I. effect on the gasoil using barium sulfonatocarbonate in quantity to impart 0.05 weightpercent of barium to the gasoil.

The curves show the calcium sulfonate is only slightly effective to reduce smoke and the effect lasts only briefly. Calcium sulfonatocarbonate is somewhat better, but its effect also is of short duration. Barium sulfonate is still better, but again the effect lasts a relatively short time.

In contrast, the compounds of this invention illustrated in curves 5, 6 and 7 are all much superior, effective for indefinite long periods to reduce the exhaust smoke, and to a much greater degree. Both curves 5 and 6 illustrate the H. I. effect and duration of barium naphthenatocarbonate and mixtures of barium naphthenatocarbonate with barium sulfonatocarbonate respectively, which are shown to be very good, each of these additives being approximately equally effective. Barium sulfonatocarbonate of Curve 7 with the same barium content, is somewhat better than the barium naphthenatocarbonate along, as illustrated in Curve 5, or its mixture with barium naphthenatocarbonate shown in Curve 6. The curves show, moreover, that the antismoke activity of the additives of the present invention operate at a markedly high level for effective smoke reduction for test periods that have been run up to 240 hours with the same Petter ABI Diesel engine, the Hartridge Index varying between the very low limits of 5 and l l EXAMPLE 5 Bench test have been carried out with a six-cylinder Leyland engine type 0/400, consuming the gasoil as in example I and the same gasoil containing the Ba sulfonatocarbonate at a 'lAltlil l llai'trirlgvv IlllliK Neutral a sul- Neutral Ila naph- (ia sul lonatu- Ha snltluniatofonatu carbonate lonatrv vnrlnmate lia sulfu- (0.015% w (0.015% w (0.05% w (1105",, w natui-arlmn- (las- (3a III (1a iii Ila iii Ba in Mixture ate (005% Test duration (hours) oil gasoil) gasoil) gasou) gasoil) 01' Ha I in gasoil) 15 14 ll) l5 l4 l0 I5 13 ll) 14 14 ll 15 14 ll) 15 12 ll) 13 13 ll 14 14 Il I5 14 J 15 13 X 14 13 I 15 12 I I3 1 1 K 15 H l') l4 l2 5 14 13 5 I4 14 ii 15 i l 0 14 I2 0 13 H 7 15 13 ii 14 14 5 l Sulionato and Ba naphthenatocarbonate (0.5% w in gasoil). *\v=Based on. D The results of this test are illustrated graphically in FIG. 1 concentration of 0.05 percent by weight of Ba in the gasoil.

wherein the Hartridge Index is plotted against the duration of the test for each of the compositions tested.

Curve No. 1 illustrates the effect of the Hartridge Smoke Index operating on untreated gasoil.

Curve No. 2 illustrates the H. I. effect on this gasoil treated with neutral calcium sulfonate added in quantity of 0.015 weight-percent based upon the weight of the calcium.

Curve No. 3 illustrates the H. 1. effect on this gasoil treated with calcium sulfonatocarbonate.

Curve No. 4 illustrates the H. I. effect on this gasoil of neutral barium sulfonate used in quantity to impart a 0.05 weight-percent of barium content to the gasoil.

Curve No. 5 illustrates the H. I. effect on this gasoil using barium naphthenatocarbonate in quantity of 0.05 weight-percent barium.

Curve No. 6 illustrates the H. 1. effect on the gasoil using a mixture of barium sulfonatocarbonate and barium naphthenatocarbonate in quantity to impart 0,05 weight-percent of barium to the solution.

The engine was run at full load with various speeds ranging from 1,200 r.p.m. to 2,400 r.p.m.; the gasoil consumption, the horsepower and the Hartridge Index were determined at each speed. The results are given in table V:

TABLE VI Gasail Gasoil plus Ba sulfonatocarbonate Con- Consum psumption Harttion HartgI./hp./ ridge Power r./hp./ ridge Power Speed (r.p.m.) hour lndex 01p.) hour Index (hp.) 1,200 161 35 65 161 5 66. 6 1,400 15!) 25 5 80. 1 ,000 150 28 H0 157 5 02. 5 1,800 162 43 102 16!) 10 105. 2,000 16!) 62 111 157 10 115. 2,200 74 118 166 28 122. 2,400 85 122 178 28 127.

The results are illustrated in FIGS. 2 and 3. FIG. 2 particularly shows curves based upon the test data set forth in table Vi which illustrate that as the engine is operated more rapidly at a higher r.p.m. the horsepower increases, as more fuel is burned, but so does the Hartridge lndex smoke effect. When the additive is present for moderate horsepowers up to 1 10, the smoke production is almost completely inhibited. At substantially higher horsepowers, up to about the limit of the engine of 127, the Hartridge index is much lower, hardly higher than the best smoking condition of the untreated fuel at the low power output. The effect to reduce smoke with increased horsepower in a diesel oil containing the additive is most marked. The power output is obviously increased, but whatever the power, the Hartridge Index is at least 50 percent lower with gasoil which contains the additive.

P10. 3 plots the fuel consumption against the horsepower of the engine. it compares in two curves the untreated gasoil with the gasoil plus the additive. For any given consumption of fuel, the power output of the engine is much greater in the fuel containing the additive.

While the data is obtained largely by test upon additive supplied to diesel oils, and is particularly useful in diesel oils which usually tend to smoke, it is also useful to reduce the smoke effect of other liquid fuels. Moreover, in addition to reducing the smoke effect, it increases the power output of the engine while maintaining the engine internally clean. Consequently, the additive will be useful for these effects with other engines. While as indicated in the general formulation the organic radical used with the barium used in the formulation of the mixed compound can vary, the product always is a mixed salt of barium with carbonic acid and a carboxylic or sulfonic acid. As shown above, notable effects result from use of as little as 0.01 percent by weight measured as barium additive in the fuel composition. it is generally preferred to use larger quantities such as 0.02 percent up to 1 percent by weight.

Certain modifications will occur to those skilled in the art, and, accordingly, it is intended that the description be regarded as illustrative and not limiting except as set forth in the claims appended hereto.

We claim:

1. Liquid hydrocarbon fuel containing a small quantity sufficient as a smoke-reducing additive to impart 0.02 to 0.25 weight-percent of barium metal in compound form to the fuel, said additive consisting essentially of a mixed barium salt of carbonic acid and an oil-soluble organic acid selected from the group consisting of carboxylic alkyl acid and benzene sulfonic acid.

2. Liquid hydrocarbon fuel containing a small quantity sufficient as a smoke-reducing additive to impart 0.02 to 0.25 weight percent of barium metal in compound form to the fuel, said additive consisting essentially of a mixed barium salt of carbonic acid and an oilsoluble organic acid mixture of carboxylic acid and sulfonic acid.

3. A liquid diesel fuel containing a small quantity sufficient as a smoke-reducing additive to impart 0.02 to 0.25 weightpercent of barium metal in compound form to the fuel, said additive consisting essentially of a mixed barium salt of carbonic acid and an oil-soluble organic acid selected from of the the group consisting of carboxylic alkyl acid and benzene sulfonic acid.

4. A liquid diesel fuel containing a small quantity sufficient as a smoke-reducing additive to impart 0.02 to 0.25 weightpercent of barium metal in compound form to the fuel, said additive consisting essentially of barium alkyl benzene sulfonatocarbonate.

5. A liquid diesel fuel containing a small quantity sufficient as a smoke-reducing additive to impart 0.02 to 0.25 weightpercent of barium metal in compound form to the fuel, said additive consisting essentially of barium naphthenatocarbonate.

6. Liquid diesel fuel containing a small quantity sufficient as a smoke-reducing additive of a mixed barium salt of carbonic acid and a keryl benzene sulfonic acid.

7. A liquid diesel fuel comprising a sulfur-containing gasoil v normally producing a substantial quantity of smoke on combustion and containing a small quantity, sufficient as a smokereducing additive, to impart 0.02 to 0.25 weight-percent based on the barium metal content of the fuel, said additive comprising a mixed barium salt of carbonic acid and an oil-soluble organic acid mixture of carboxylic acid and sulfonic acid.

8. A concentrate useful as a smoke-reducing additive upon dilution in a liquid fuel to a concentration in the range of about 0.01 to 0.25 percent by weight based upon the barium metal content imparted to the liquid fuel, said concentrate consisting of from 30 to 50 percent by wei ht of a mixed barium salt of carbonic acid and an oil-so uble organic acid selected from the group consisting of carboxylic acid and alkyl benzene sulfonic acid, and the balance, 50 to percent, being substantially hydrocarbon oil.

9. The concentrate of claim 8 wherein the additive compound is barium alkyl benzene sulfonatocarbonate.

10. The concentrate of claim 8 wherein the additive compound is barium naphthenatocarbonate.

11. A concentrate useful as a smoke-reducing additive upon dilution in a liquid fuel to a concentration in the range of about 0.01 to 0.25 percent by weight based upon the barium metal content imparted to the liquid fuel, said concentrate consisting of from 30 to 50 percent by weight of a mixture of barium sulfonatocarbonate and barium naphthenatocarbonate, and the balance of 50 to 70 percent being substantially hydrocarbon oil.

12. A method of burning a diesel fuel tending to produce smoke, comprising burning said fuel in the presence of a small quantity, sufficient to reduce smoke, of an additive comprising a mixed basic barium salt of carbonic acid and an oil-soluble organic carboxylic acid.

13. A method of burning a diesel fuel tending to produce smoke comprising burning said fuel in the presence of a small quantity, sufficient to reduce smoke, of an additive comprising a mixed basic barium salt of carbonic acid and alkyl benzene sulfonic acid.

14. A method of burning a diesel fuel tending to produce smoke, comprising burning said fuel in the presence of a small quantity, sufficient to reduce smoke, of an additive comprising a mixed barium salt of carbonic acid and an oil-soluble organic acid mixture of carboxylic acid and sulfonic acid.

UNITED STATES PATENT OFFICE CERTIFICATE OF COR-ECTIGN Patnt 3.637.356 Dated January 25, 1972 fls) Andre Jacques Emile Vanderlinden, et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet ['73] Assignee, "Big Springs, 'I ex." should read Big Spring, Tex. Column 2, line 33, "contain" should read contained- Column 6, line 20, "along" should read alone line 25, "ABl" should read AVl line 30, "test" should read tests Column 7, lines 46 and 59, cancel "alkyl"; same lines insert alkyl after "and" Signed and sealed this 14th day of November 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 60376-1 69 v: u.s. GOVERNMENT PRINTING OFFICE: 1959 o-aes-su, I 

2. Liquid hydrocarbon fuel containing a small quantity sufficient as a smoke-reducing additive to impart 0.02 to 0.25 weight percent of barium metal in compound form to the fuel, said additive consisting essentially of a mixed barium salt of carbonic acid and an oil-soluble organic acid mixture of carboxylic acid and sulfonic acid.
 3. A liquid diesel fuel containing a small quantity sufficient as a smoke-reducing additive to impart 0.02 to 0.25 weight-percent of barium metal in compound form to the fuel, said additive consisting essentially oF a mixed barium salt of carbonic acid and an oil-soluble organic acid selected from of the the group consisting of carboxylic alkyl acid and benzene sulfonic acid.
 4. A liquid diesel fuel containing a small quantity sufficient as a smoke-reducing additive to impart 0.02 to 0.25 weight-percent of barium metal in compound form to the fuel, said additive consisting essentially of barium alkyl benzene sulfonatocarbonate.
 5. A liquid diesel fuel containing a small quantity sufficient as a smoke-reducing additive to impart 0.02 to 0.25 weight-percent of barium metal in compound form to the fuel, said additive consisting essentially of barium naphthenatocarbonate.
 6. Liquid diesel fuel containing a small quantity sufficient as a smoke-reducing additive of a mixed barium salt of carbonic acid and a keryl benzene sulfonic acid.
 7. A liquid diesel fuel comprising a sulfur-containing gasoil normally producing a substantial quantity of smoke on combustion and containing a small quantity, sufficient as a smoke-reducing additive, to impart 0.02 to 0.25 weight-percent based on the barium metal content of the fuel, said additive comprising a mixed barium salt of carbonic acid and an oil-soluble organic acid mixture of carboxylic acid and sulfonic acid.
 8. A concentrate useful as a smoke-reducing additive upon dilution in a liquid fuel to a concentration in the range of about 0.01 to 0.25 percent by weight based upon the barium metal content imparted to the liquid fuel, said concentrate consisting of from 30 to 50 percent by weight of a mixed barium salt of carbonic acid and an oil-soluble organic acid selected from the group consisting of carboxylic acid and alkyl benzene sulfonic acid, and the balance, 50 to 70 percent, being substantially hydrocarbon oil.
 9. The concentrate of claim 8 wherein the additive compound is barium alkyl benzene sulfonatocarbonate.
 10. The concentrate of claim 8 wherein the additive compound is barium naphthenato carbonate. A concentrate useful as a smoke-reducing additive upon dilution in a liquid fuel to a concentration in the range of about 0.01 to 0.25 percent by weight based upon the barium metal content imparted to the liquid fuel, said concentrate consisting of from 30 to 50 percent by weight of a mixture of barium sulfonatocarbonate and barium naphthenatocarbonate, and the balance of 50 to 70 percent being substantially hydrocarbon oil.
 12. A method of burning a diesel fuel tending to produce smoke, comprising burning said fuel in the presence of a small quantity, sufficient to reduce smoke, of an additive comprising a mixed basic barium salt of carbonic acid and an oil-soluble organic carboxylic acid.
 13. A method of burning a diesel fuel tending to produce smoke comprising burning said fuel in the presence of a small quantity, sufficient to reduce smoke, of an additive comprising a mixed basic barium salt of carbonic acid and alkyl benzene sulfonic acid.
 14. A method of burning a diesel fuel tending to produce smoke, comprising burning said fuel in the presence of a small quantity, sufficient to reduce smoke, of an additive comprising a mixed barium salt of carbonic acid and an oil-soluble organic acid mixture of carboxylic acid and sulfonic acid. 